Silicone emulsions have been used in various fields not only as a protective material for home use products, travel goods, ships or automobile parts made of polyvinyl chlorides, or the like, but also as a glazing agent for improving the appearance of those goods.
A diluted silicone emulsion can be used as a material for treating textiles, interior decorations, cloth-coverings, or the like. It is possible, by treatment with such a silicone emulsion, to impart excellent water-resistant and dust-proof properties to textiles and the like.
In addition, much attention has been directed to the use of silicone emulsions in a variety of cosmetics, such as hair conditioners, make-ups, anti-sunburn lotions, and the like.
Because of the stability of micelles and fine particle size, it can be advantageous to produce silicone emulsions by means of emulsion polymerization.
Emulsion polymerization is a process in which a low molecular organosiloxane is dispersed into an aqueous medium by use of an emulsifier and then polymerized up to a desired polymerization degree in the presence of a polymerization catalyst, as is described, e.g., in U.S. Pat. No. 2,891,920.
Upon such emulsion polymerization, there is usually used an organic sulfonic acid ester which functions not only as an emulsifier but also as a catalyst, such as those described in U.S. Pat. Nos. 3,360,491 and 3,294,725, in particular dodecylbenzene sulfonates, because of their ease of production and cost.
However, silicone emulsions produced in accordance with such an emulsion polymerization process suffer from the disadvantage that they, owing to sulfur atoms remaining therein, are easily colored yellow when exposed to ultraviolet rays.
For the purpose of preventing such coloring, it has been attempted to reduce the quantity of organic sulfonates to be used as an emulsifier catalyst and to reduce the quantity of sulfur remaining in the resulting silicone emulsions.
However, a simple reduction of the amount of organic sulfonates used results in a lowering in the conversion rate of low molecular organosiloxanes and a lowering in the polymerization degree of polyorganosiloxanes obtained.